兰新第二双线戈壁土路基填料填筑试验研究

Experimental Study on Gobi Soil as the Filling Material for Subgrade Construction of the Second Double-Track for Lanzhou-Xianjiang Railway

在兰新铁路第二双线某试验段分别采用重锤夯实、冲击碾压和重型碾压处理的地基上,进行以戈壁细圆砾土为填料的现场路基填筑压实试验研究。研究结果表明,采用戈壁细圆砾土作为填料时,填料的粒径应在6cm及以下,并采用取土场挖坑灌水渗透方法进行填料拌水施工;填筑的松铺系数为1.1,基床底层和基床以下路堤的虚铺厚度分别为35和40cm,最优含水率为3%,最佳碾压方式为静压1遍、强振3遍、弱振2遍、再静压2遍;为加快路基压实质量的检测速度,建议现场检测压实质量以地基系数K30和压实度K或孔隙率n为主控指标,且基床以下路堤的孔隙率n≤23%,基床底层路堤的孔隙率n≤21%;用3种地基处理方法处理后的路基经堆载预压,其沉降稳定较快,工后沉降均满足铺设无砟轨道的设计标准。

Field compaction test for Gobi fine round gravel soil was studied in a test section of the second double-track of Lanzhou-Xinjiang Railway,in this section the ground was treated with hammer compaction,impact rolling and heavy rolling.The results show that if Gobi fine round gravel soil is used as filling,the maximum particle size should be 6 cm,the filling should be mixed with water in field borrow pit.The loose paving coefficient of the filling material for subgrade is 1.1.The loose paving thickness of the embankment of roadbed bottom and below roadbed is 35 and 40 cm respectively.The optimum moisture content is 3%,and the optimum grinding and compaction method is 1 static compacting,then 3 strong shaking,2 weak shaking,and finally 2 static compacting.For quickening the detection speed of subgrade compaction quality,it is suggested that ground coefficient K30,compaction coefficient K or porosity n should be taken as the master control indexes.The porosity n of the embankment below roadbed should be less than or equal to 23%,and the one of roadbed bottom should be less than or equal to 21%.After the preloading of subgrade on ground treated with 3 methods,the settlement stabilizes quickly and the post-construction settlement meets the design standard for paving ballastless track.